Controllable precession gyroscope

ABSTRACT

A gyroscope for generating a drift rate for an optical lead computing gun sight including a particular flexure plate for mounting the gyroscope eddy-current disc and a four pole permanent magnet of a particular configuration which provides a fail-safe function in the device.

Unite States ate Tddings Aug. 28, 1973 CONTROLLABLE PRECESSION 3,498,1463/1970 Hulle et a1. 74/5.46 x 3,543,301 11/1970 Barnett 74/5 F GYROSCOPE3,597,938 8/1971 Hellen et a1. 308/2 A .l Inventor: Lloyd g Arlington,3,354,726 11/1967 Krupick et a1 74/5 F [73] A S Signee: The UnitedStates of Am erica as represented by the Secretary of the Navy PrimaryExaminer-Manuel A. Antonakas [22] Filed: Jan. 10 1972 Attorney-R. S.Sciascia et a1.

21 Appl. No.: 216,434

[57] ABSTRACT 4 F fi 8' 222, 5 A gyroscope for generating a drift ratefor an optical 58] Fieid 4/5 F 5 lead computing gun sight including aparticular flexure plate for mounting the gyroscope eddy-current discand a four pole permanent magnet of a particular configu- 56] ReferencesCited ration which provides a fail-safe function in the device.

UNITED STATES PATENTS 2,916,919 12/1959 Echolds 74/546 3 Claims, 6Drawing Figures 1 CONTROLLABLE PRECESSION GYROSCOPE BACKGROUND OF THEINVENTION 1. Field of the invention The present invention relates to agyroscope and more particularly to an eddy-current constrained gyroscopefor a gun sight unit wherein a rotating reflecting mirror is used toprovide lead angular deviations.

2. Description of the prior art U. S. Pat. No. 2,916,919 to Echoldsshows an insideout gyroscope of the general type of the instantinvention. One of the problems of manufacturing gyroscopes of this type,is the lack of compactness and economy of manufacture in the gimble ringarrangements which mount the eddy-current disc and the gyroscope rotor.Another problem is the heat buildup in this type of gryoscope due to themultitude of electromagnetic coils. A still further problem with theconventional gyroscopes as represented by the patented gyroscopereferred to above, is that malfunction of the range coils makes thedevice inoperable. A difficulty with using multiple permanent magnets ingyroscopic devices, for example as shown in US. Pat. Nos. 2,368,644 and2,390,532, is in obtaining and maintaining a constant and equal flux inall of the individual'permanent magnets.

SUMMARY OF THE INVENTION The present invention provides a gyroscope forgenerating a drift rate when optical lead computing gun sight whichincludes a flexure plate which is compact, economical to produce, withflexure qualities which are easy to control in the manufacturingprocess. The device also incorporates a permanent magnet having fourpoles of equal and relatively constant flux to produce a fail-safegyroscopic device.

OBJECTS OF THE INVENTION An object of the present invention is toproduce a fail-safe gyroscope for generating a drift rate for an opticallead computing gun sight.

Another object is to prevent heat buildup in a gyroscopic device.

Another object is to produce an'equal flux density in each of severalpoles of a gyroscopic device.

Still another object is to produce a compact gyroscope.

A still further object is to produce a gyroscope with a flexure joint ofprecise flexure qualities.

Other objects, advantages, and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-sectionalview of the gyroscope;

FIG. 2 is a plan view of the flexure plate;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a cross-sectional view of the permanent magnet used in thepresent invention;

FIG. 5 is a top view of the permanent magnet asshown in FIG. 4; and

FIG. 6 is a bottom assembly view of one of the electromagnetic coils,the permanent magnet, anda part of the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawings, wherein like reference characters designate like orcorresponding parts throughout the several views, there is shown acasing l 1 to which four outer soft iron deflection poles 12-15,inclusive, are inwardly directed. Each of the outer deflection poles12-15 has a coil wound thereon, coil 16 (not shown) and 17 serving aselevation coils, and coil 18 and 19 (not shown) serving as azimuthcoils.

The annular channel 24 has four inner pole sections 26-29 and each ofthese poles has its end in close proximity to one of the ends of theouter deflection poles 12-15. It can be seen there are only small airgaps between the outer and inner deflection poles, which provide anearly closed flux path. The four poles 55-58 of the permanent magnetare interposed between the outer deflection poles 12-15. Range permanentmagnet 50 consists generally of an annular portion 51 with fourfinger-like projections or poles 55-58 which fit between deflectionpoles 12-15 as best seen in FIG. 6. The finger-like projections 55-58are of like polarity and produce flux patterns of equal configurationsand intensity. Permanent magnet 50 is ideally chosen to have a fluxdensity which corresponds to the firing range of forward firing aircraftmachine guns at their point of convergence. The effective flux ofpermanent magnet 50 is controlled by range coil 23 which is supported inannular channel 24, which is fastened to casing 11. Range coil 23 mayadd or substract from the constant flux of permanent magnet 50 throughinner pole sections 26-29. The permanent magnet 50 eliminates the needfor the other electromagnetic range coil used in prior gyroscopicsystems of this type. This reduces heat buildup and produces anextremely accurate device which is fail-safe in that there is one lesselectromagnetic range coil which might malfunction and even if theremaining range coil 23 does not produce a flux, for example due to amalfunction, the device of the present invention would produce thedesired lead for the normal range, e.g. the convergence point of theaircraft guns.

Cylindrical member 29 is attached to the annular channel 24 and flexureplate is mounted in the cylindrical member 29 by means of bolts 77. Theflexure plate 70, as best seen in FIGS. 2 and 3, has outer semicircularslots 71 and 72 and inner slots 73 and 74. The inner slots 73 and 74 aredisposed approximately 90 out of phase with respect to outer slots 71and 72. Each end of each of the slots 71-74 have counterbores 75 at theends thereof. The size and depth of counterbores 75, along with thematerial and thickness of plate 70 primarily determine the flexurequalities. The counterbores may be of equal or unequal depth or size onopposite'sides of the plate for example. By drilling deep counterbores75 the plate will flex more easily along pivotal flexure points 76, ofcruciform cross-section as seen in FIG. 3.

A shaft 36 is rotatably mounted in bearings, one bearing 37 being withinthe cup-shaped member 34 and another bearing 38 being within the flexureplate 70. Shaft 36 has attached on one end a cup-shaped rotor 39, and ahysteresis ring 41, made of a material having a high hysteresisconstant, for example a cobolt alloy, is attached to the inner peripheryof the cup-shaped rotor 39. The cup-shaped rotor 39 is made of anon-ferromagnetic material, for example stainless steel. A mirror 42 isattached to the front face of the cup-shaped rotor 39.

An eddy-current disc 43 is attached to the other end of shaft 36 and ispositioned in the air gaps between the inner and outer deflection poles.

In operation, the cup-shaped rotor 39 is rotated at a relatively highspeed when current is applied to the field armature 35. Since the mirror42 is attached to the front face of rotor 39, the mirror 42 will berotated at the speed the rotor is rotating. Shaft 36 will also be drivenby the rotor and consequently the eddy-current disc 43 will be spinningin the space between the inner and outer deflection poles. Current isalso applied to the control coils 16-19, inclusive, and a magnetic fieldis produced. When this field is cut by the spinning disc 43,eddy-currents are produced in the disc. These eddy-currents areelectrical currents which flow in small closed paths and the reaction ofthe field of these currents with the primary magnetic field createsforces which oppose the motion of disc 43. The magnitude of theeddy-current forces may be controlled by the strength of the magneticfield and by controlling the current applied to the control coils,thereby controlling the position of disc 43 in azimuth and elevation. Asnoted above, permanent magnet 50 sets the device at a predeterminedrange by selection of the proper flux therefor. The sensitivity of thedevice is then controlled by the amount of current applied to range coil23.

When disc 43 is changed in position, mirror 42 will also be moved sinceshaft 36 physically connects mirror 42 and disc 43. Thus it can be seenthat an image, such as a reticle pattern, can be deviated to provide forthe proper lead necessary in the firing of a trajectory.

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An eddy-current constrained gyroscope comprising:

a casing;

means for rotatably and pivotally mounting a shaft to said casingcomprising a flexure plate having a first outer semicircular slot on oneside of said plate;

a second outer semicircular slot on the otherside of said plate,

said first and second outer semicircular slots being separated at theends thereof by portions of said plate, 7

a first inner semicircular slot on a first side of said plate,

a second inner semicircular slot on a second side of said plate,

said first and second inner semicircular slots being separated at theends thereof by portions of said plate,

said semicircular slots being counterbored at the ends thereof;

a hysteresis motor mounted within said casing having a stator attachedto said mounting means and a rotor attached to said shaft;

a mirror attached to one face of said rotor;

an eddy-current disc attached to said shaft;

a permanent magnet for producing a magnetic field across theeddy-current disc; and

a plurality of coils attached to said casing providing variable magneticfields across the eddy-current disc to vary the magnetic field producedby the permanent magnet.

2. The device of claim 1 wherein a range coil further controls themagnetic field across the eddy-current disc.

3. The device of claim 1 wherein said permanent magnet is annular withfour radially projecting poles thereon.

1. An eddy-current constrained gyroscope comprising: a casing; means forrotatably and pivotally mounting a shaft to said casing comprising aflexure plate having a first outer semicircular slot on one side of saidplate; a second outer semicircular slot on the otherside of said plate,said first and second outer semicircular slots being separated at theends thereof by portions of said plate, a first inner semicircular sloton a first side of said plate, a second inner semicircular slot on asecond side of said plate, said first and second inner semicircularslots being separated at the ends thereof by portions of said plate,said semicircular slots being counterbored at the ends thereof; ahysteresis motor mounted within said casing having a stator attached tosaid mounting means and a rotor attached to said shaft; a mirrorattached to one face of said rotor; an eddy-current disc attached tosaid shaft; a permanent magnet for producing a magnetic field across theeddy-current disc; and a plurality of coils attached to said casingproviding variable magnetic fields across the eddy-current disc to varythe magnetic field produced by the permanent magnet.
 2. The device ofclaim 1 wherein a range coil further controls the magnetic field acrossthe eddy-current disc.
 3. The device of claim 1 wherein said permanentmagnet is annular with four radially projecting poles thereon.